/Engine/Source/Editor/ViewportInteraction/Public/VIBaseTransformGizmo.h
Called by the world interaction system when one of our components is dragged by the user to find out what type of interaction to do. If null is passed in then we'll treat it as dragging the whole object (rather than a specific axis/handle)
[UViewportDragOperationComponent](API\Editor\ViewportInteraction\UViewportDragOperationComponent) * GetInteractionType ( [UActorComponent](API\Runtime\Engine\Components\UActorComponent) * DraggedComponent, [TOptional](API\Runtime\Core\IO\TOptional)< [FTransformGizmoHandlePlacement](API\Editor\ViewportInteraction\FTransformGizmoHandlePlacement) > & OutHandlePlacement )